Vehicle control method and vehicle warning method

ABSTRACT

In order to occur a collision warning to prevent the collision in accurate by detecting the preceding vehicle or target, a vehicle lane position estimation device comprising a means for measuring a distance between said host vehicle and said preceding vehicle or a oncoming vehicle, a direction angle from said host vehicle, an angular velocity and a velocity of said host vehicle, a means for calculating lateral and longitudinal distance between said host vehicle and said preceding vehicle or said oncoming vehicle, a means for capturing a front stationary object, a means for obtaining movement of the preceding vehicle or position of the oncoming vehicle, and a means to estimate a lane position of said front stationary object from a relationship of the stationary object being captured and the preceding vehicle being obtained and a positional relationship with the oncoming vehicle.

This is a continuation of application Ser. No. 09/605,052 filed Jun. 28,2000 now U.S. Pat. No. 6,311,123.

BACKGROUND OF THE INVENTION

1. The Technical Field that the Invention Belongs to

The present invention relates to an estimation device using a radar todetect dangerous objects for a vehicle.

Especially the present invention relates to the estimation device fordistinguishing various kinds of non-dangerous objects which aregenerally met in typical vehicle driving environment and the dangerousobjects which are authenticity.

2. Prior Art

A lot of trials to discriminate the dangerous objects that can betrusted, were performed in a field of a vehicle radar system to measurea distance to the dangerous objects and a relative velocity thereof.

In a Japanese Patent Laid-open No. 6-282798 bulletin, a target searchdevice is mentioned, the target search device comprising a targetcapture means to capture the target by searching periphery of a servicebody and to get a relative position of the target to the service body, acircular orbit estimation means to estimate a circular orbit of theservice body in a turning motion of the service body, based on therelative position of the target which the target capture means got andthe circular orbit of the service body (4) which the circular orbitestimation means estimated, and a control means to judge whether thetarget is located in the circular orbit and to distinguish the targetlocated on a course of the service body.

In a Japanese Patent Laid-open No. 8-83400 bulletin, a method todistinguish dangerous objects for the vehicle from the objects which isnot the dangerous objects in the vehicle radar system which can detectat least one object on the road near the vehicle driving in the firstvehicle lane is mentioned, said method comprising the steps of a step togenerate a radar beam having enough beam width to irradiate the objectin the first vehicle lane and a second vehicle lane which is nextthereto, and at least a part of the radar beam generated along a firstaxis which is generated in a right angle substantially, a step toreceive a message of a reflex signal from the object irradiated, a stepto estimate a velocity of the object irradiated about a vehicle velocityin a direction of the second axis (x) which is substantially parallel tothe service direction of the vehicle based on reflection signal, a stepto measure the velocity of the vehicle using at least one velocitysensor, a step to judge the irradiated object to be dangerous when a sumof measured the vehicle velocity and estimated the velocity which isparallel to the object is bigger than a predetermined threshold, and astep to judge the irradiated object not to be dangerous when a sum ofmeasured the vehicle velocity and estimated the velocity which isparallel to the object is smaller than the predetermined threshold.

SUMMARY OF THE INVENTION

The Subject that Invention is Going to Solve

A sensing requirement for a system should be thinking about as that adistance with a preceding vehicle(including stopping vehicle and anobject, herein after called as a target) is controlled to be a desiredvalue (ACC: Adaptive Cruise Control) by detecting the lead car inforward of host vehicle lane, or a collide warn is occurred when comingtoo much close to the preceding vehicle or the target.

For example, following three phases may be considered.

The first step: A detectivity ability, that is, may the forward target(the vehicles and road side object) be recognized?

i) A distance to the target (max especially), relative velocity anddetectivity power of angle.

ii) An accuracy of the vehicle lane judgment of the host vehiclelane/others vehicle lane.

The second step: Discrimination ability, that is, may the forward targetbe recognized?

Especially, is the forward stationary object in forward of the hostvehicle discriminated? (For example, the road side object such as astationary vehicle, a corner pole and road signs, and an object on theroad such as an overhead bridge can be distinguished?)

The third step: Intention decision, that is, which direction is thedriver going to go to?

Is the forward obstacle included in a driving path in the future basedon the driver intention? (there is no need to occur the warning when notincluded.)

Referring to the above, an object of the present invention is to providea vehicle lane position estimation device of the preceding vehicle orthe target by improving the vehicle lane decision accuracy of the hostvehicle lane/others vehicle lane and by detecting the preceding vehiclein forward of the host vehicle lane or the target, so that the distancewith the preceding vehicle is controlled to be a desired value or acollision warning to prevent the collision with the target is generatedin accurate.

Further, another object of the present invention is to provide a vehiclelane position estimation device of the forward stationary object whichmay recognize in accurate whether the stationary object is a dangerousobjects on the host vehicle lane or not or whether it is on the hostvehicle lane or not.

Further, another object of the present invention is to distinguish thestopping preceding vehicle and the stationary object such as a road signon the road side or an overhead bridge, and to warn or control(decelerate) the stopping vehicles which is in forward of the hostvehicle.

A Means to Solve the Subject

According to the present invention, algorithm for estimating the hostvehicle lane to be accurate in a curved road and for estimating anaccurate correction when a position correction is necessary, is providedon the basis of a movement of the preceding vehicle which the radarcaught and other sensor information, various data from the vehicles sideare received, vehicle lane position estimation of the preceding vehicleis performed with a sensing information got by a millimeter wave radar,and a one body type millimeter wave radar system is built in acommunications network function that can transmit an warning or acontrol command information to the vehicle side and decision/controlfunction, is provided.

In such the vehicle lane position estimation device as above, thepresent invention further comprising a means for judging whether a curveof said road is a transition curve section where a curvature radiusthereof changes every moment sometimes, or a maximum curve section wheresaid curvature radius does not changes, and a means for correcting acurvature radius Rf of said host vehicle used for correcting saidcurvature radius Rf of said preceding vehicle to be smaller than apredetermined value when a transition curve is in an introduction partof the curve, and for correcting said curvature radius Rs to be largerthan said predetermined value when said transition curve is in an rearpart of the curve.

In such the vehicle lane position estimation device as above, a vehiclelane boundary position is obtained by estimating a vehicle lane positionof plural preceding vehicle, the host vehicle is judged to be right orleft of the vehicle lane boundary, and a vehicle lane judgment positionof said host vehicle is offset towards right or left.

In such the vehicle lane position estimation device as above, thepresent invention further comprising a millimeter wave radar and a gyrosensor are used as said means for measuring.

In such the vehicle lane position estimation device as above, thepresent invention further comprising a means obtaining a distance of thevehicles from said preceding vehicle, and a means for warning when saiddistance becomes a predetermined distance.

The present invention relates to a vehicle lane position estimationdevice for estimating a position of a vehicle lane of a stationaryobject (a forward stationary object) to be located before an hostvehicle, comprising a means for measuring a distance between said hostvehicle and said preceding vehicle or an oncoming vehicle, a directionangle from said host vehicle, an angular velocity and a velocity of saidhost vehicle, a one vehicle lane sensing means for obtaining a vehiclelane of a road, a means for calculating a lateral displacement betweensaid host vehicle and said preceding vehicle or said oncoming vehicle, alongitudinal displacement therebetween and a curvature radius of saidhost vehicle, a means for capturing a forward stationary object, a meansfor obtaining a movement of said preceding vehicle or a position of saidoncoming vehicle, a means for estimating a vehicle lane position of saidforward stationary object from a movement relationship of said precedingvehicle obtained and said forward stationary object captured or aposition relationship with said oncoming vehicle, and a means forwarning when said forward stationary object is in a vehicle lane of saidhost vehicle.

In such the vehicle lane position estimation device as above, thepresent invention further comprising a means for recognizing whethersaid forward stationary object is an object on the road such as anoverhead bridge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a contour block diagram of a distance between vehicles alarmsystem.

FIG. 2 is a contour block diagram of an ACC system.

FIG. 3 is a control block diagram.

FIG. 4 is a figure of account system.

FIG. 5 is a curvature radius illustration.

FIG. 6 shows related figures of the curvature change and the correction.

FIG. 7 is a figure of a flow chart of a correction step.

FIG. 8 is a contour block diagram of a distance between vehicles alarmsystem.

FIG. 9 is a contour block diagram of the ACC system.

FIG. 10 is illustration to discriminate an overhead bridge and astopping vehicle.

FIG. 11 is a contour block diagram of a distance between vehicles alarmsystem.

FIG. 12 is a contour block diagram of an ACC system.

FIGS. 13A and 13B show figures to discriminate a curve and a vehiclelane change of a preceding vehicle.

FIG. 14 is a flow chart of the discrimination method.

FIG. 15 is a flow chart of host vehicle lane position estimation.

FIGS. 16A and 16B show figures of the preceding vehicle and thestationary object recognition and moving velocity.

FIG. 17 is a figure of transverse direction transfer of the curve andthe vehicle lane change.

FIG. 18 is a figure of the oncoming vehicle and the stationary objectrecognition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will be explained based on adrawings.

FIG. 1 shows a distance between the vehicles alarm system 1 using amillimeter wave radar, a gyro sensor, or a steering sensor.

The figure shows a system configuration in a case that a millimeter waveradar signal is generated from a radio antenna unit 4 toward a vehicle 3from a host vehicle 2, and warn when approaching.

The distance between the vehicles·the relative velocity·the angle withpreceding vehicle 3 is measured with a unit 5 by a conventional methodusing a radio antenna unit 4 of the millimeter wave radar.

Measurement is performed with a unit 8 by measuring the angular velocityby a gyro sensor 6, and the steering angle is measured by steeringsensor 7 with a unit 9.

By the measured angular velocity and the steering angle, a vehicle laneis judged with a unit 10 according to an algorithm mentioned later.

The preceding vehicle judgment with a unit 11 and stationary objectjudgment with a unit 12 in forward of the host vehicle are performed bythe distance between the vehicles·the relative velocity·angle (precedingvehicle 3) which are measured and vehicle lane judgment.

Based on these judgments, an warning judgment with a unit 14 is done byusing the warning judgment algorithm with a unit 13, and a vehiclevelocity and a braking signal with a unit 26.

Based on the warning judgment, an warning designation with a unit 15 isperformed, and an alarm signal 16 is given, and an alarm soundgeneration, lighting and display are performed in a driver display unit17.

FIG. 2 shows an other embodiment of the present invention, using amillimeter wave radar, a gyro sensor, or a steering sensor.

ACC system 21 is shown to drive following a preceding vehicle keeping apredetermined distance between the vehicles.

A millimeter wave radar signal is given from a radio antenna unit 4toward a driving vehicle 3 from the host vehicle 2, a preceding vehicledetection with a unit 22 and a stationary object sensing 23 areperformed by measuring the distance between the vehicles·the relativevelocity·the angle and the vehicle lane judgment.

Based on these sensing, an accelerating and a decelerating judgment witha unit 25 is done by using the distance control algorithm 24 between thevehicles, a vehicle speed signal, and a braking signal 26.

Based on the judgment result, a vehicle speed holding and theaccelerating/decelerating speed signal are given with a unit 27, thedistance control between the vehicles with a unit 28 comprising aslottle control 29, a A/T shift control 30, and a braking control 31 isdone.

In addition to above, the system of FIG. 1, FIG. 2 namely alarm systemand an ACC system do not always exist only as separated system, but asystem configuration having both function can be taken.

In next, FIG. 3 shows a hardware configuration to realize an embodimentof the system by FIG. 1 and FIG. 2 with a block diagram.

The construction shown in the figure are a one body type millimeter waveradar system 35, a vehicles side control part 36, and a display unit 37for a driver.

The one body type millimeter wave radar system 35 has, for example, acommunication network facility that used CAN, for example, and isconstituted with a vehicles side control part 36, a driver display unit37 and a communications network.

In the figure, a radar sensing signal obtained by a transmitting antenna41 built in a unit 35, a receiving antenna 42 and a high frequencycircuit 43, and an analog signal from the gyro sensor 6 are converted byan AD conversion 44, and are done signal processing by a digital signalprocess circuitry 45 (constituted with CPU, DSP etc.)

Said digital signal process circuitry 45 is installed a software asbuilt-in software 47, in order to process a risk judgment and an warningorder in an warning and an ACC following order and an acceleratingdeceleration orders ets. in the ACC based on the radar signalprocessing, preceding vehicle trapping, host vehicle lane judgment, etc.

As for these various signals, they are communicated through acommunications network 38 and a data communication part 46.

The driver display unit 37 generate the alarm, do lighting and displaythe distance with the preceding vehicle according to a communicationsignal received.

According to setting modification of the driver to reverse, anadjustment of the distance that the warning occurs in the warning isperformed, and the adjustment signal of the distance between the hostvehicle and the preceding vehicle in the ACC is transmitted to the unit35. In the digital signal attention circuitry 35, modification of thevarious parameter is enforced based on said adjusting signal.

The vehicle side control part 36 is used in order to constitute the ACCsystem.

This is constituted with an engine control unit 51, an AT control unit52 and a braking control unit 53, the engine output, the AT shiftposition, and the automatic braking in order to slow down suddenly areperformed in order to accelerate and to decelerate the vehicle byreceiving a signal from the one body type millimeter wave radar system35.

The vehicle side control part 36 is inputted various sensor signalswhich are necessary for controlling in the vehicle side, for example, agyro sensor signal 6, a steering sensor signal 7, a vehicle speed sensorsignal 26, a braking signal 260, a wheel velocity sensor signal 54, ashift position sensor signal 55, an acceleration sensor signal 56 etc.

And, the signals which are necessary for the one body type millimeterwave radar system 35 side, for example, the vehicle velocity sensorsignal 26 and the steering sensor signal 7 are transmitted through acommunications network 38.

In these system configuration, as the vehicle side control part 36 is aconventional technique and it is not described moreover in detail.

In next, in said built-in software 47, a method to judge vehicle lane ina curved road and a derivation of operating equation will be explained.

FIG. 4 shows a relationship between a own car which is on a circlecontour of a curvature radius Rs and a lead car which is on Rf.

Judging from the host vehicle, whether the preceding vehicle is on thehost vehicle or on an adjacent vehicle lane, can be judged by adifference ΔR of the curvature radius between the host vehicle and thepreceding vehicle originally.

Method of operation will be explained as follows.

1. A distance Tr and a magnetic declination degree α are measured byusing the millimeter wave radar, and a host vehicle angular velocity ωsand a host vehicle velocity Vs is measured with the built-in gyro sensor6.

2. A side displacement TC, a longitudinal displacement TD and a hostvehicle curvature radius Rs are calculated with the next equations.

T _(C) =T _(R) sin α,T _(D) =T _(R) cos α,R=Vs/ωs

3. As shown in FIG. 4, as for the rotation radius Rf of the precedingvehicle, the next equation is obtained.

 Rf ² =Rx ² +TD ²=(Rs−TC)² +TD ²

4. Therefore, the next equation is obtained.

Equation 2

ΔR=Rf−Rs={square root over ((Rs−Tc)2+Td2−Rs)}  (Equation 2)

Here Ly is defined as a vehicle lane width.

Equation 3

|ΔR|<Ly/2(Ly: one vehicle lane)  (Equation 3)

The vehicle lane of the host vehicle is judged when the above equationis satisfied.

The value of Ly is not be a half vehicle lane width which is symmetricfor an host vehicle because the host vehicle may not go on a center ofthe vehicle lane.

The setting method of the value is disclosed in an embodiment explainedlater.

Using FIG. 5 and FIGS. 6A, 6B in the next, a correction method of thecurvature radius Rf of the preceding vehicle will be explained.

Currently, the position of the preceding vehicle in a curved road isestimated by correcting on the basis of the angular velocity measuredwith the gyro sensor.

In this correction method to use the angular velocity of the hostvehicle, the preceding vehicle is calculated to be on a circle extendedfrom a rotation center of the position which is same as the current hostvehicle.

However, a real road does not consist of only a linear lane and a curvelane, and “a transition curve” section which is joined therebetween bychanging R by degrees exists by all means.

Accordingly, even if it is assumed that the angular velocity is measuredgood enough in accurate, a right measurement is only performed when bothof the preceding vehicle and the host vehicle is in a circle contour ora linear line.

Accordingly, it becomes important that this transition curve is detectedand the R is corrected in suitable.

FIG. 5 shows a transition section 62 connected to a linear line section61, a constant R section 63, a transition section 64, and a linear linesection 65 connected to said transition section 64.

In other words, the R becomes small (the angular velocity increases) inthe transition section 62 by degrees, the R becomes constant (angularvelocity constant) in the constant R section 63 (circle contoursection), the R increases by degrees (angular velocity decrease) whencoming in a reverse transition section 64, and it is returned to alinear line section (In the linear line, R=∞).

Accordingly even if it is assumed that the preceding vehicle and thehost vehicle ran at the same vehicle lane center, when the host vehicleis on the transition section 62, the preceding vehicle travels on thesmall R than this section 62, and reversely, when the host vehicle is onthe transition section 62, the preceding vehicle travels on a bigger Rthan a detected R of the host vehicle.

FIGS. 6A, 6B shows a change of the angular velocity ωR, a change of thecurvature radius R, and a correction direction of the R detected whendriving the curve.

Shown in the figure, the R is corrected in the transition section 62 alittle to be (R−ΔR), the R is constant in the constant R section 63, theR is corrected greatly in the transition section 63 as (R+ΔR) so as toestimate the lane of the preceding vehicle.

Here, it is assumed that the preceding vehicle is followed by a statuswithout relative velocity with the host vehicle.

Then the R is corrected using sensor information such as

1. A distance d with the preceding vehicle, and a magnetic declination θand The change Δθ,

2. An angular velocity ωR every moment, and a change ΔωR thereof,

3. A steering angle φ and a change velocity δφ thereof.

FIG. 7 is a flow chart showing a correction step.

At first, in a step 701, a distance d(t) with the preceding vehicle at atime t, the preceding vehicle magnetic declination θ(t), the angular thevelocity ωR(t) and the steering angle φ(t) is detected and is stored.

In a step 702 in the next, a change Δθ(t), ΔωR(t) and δφ(t) of θ(t),ωR(t), φ(t) are obtained by performing a differentiation filterprocessing using past time t-1, t-2, . . . .

In a step 703, absolute values |Δθ(t)| and |δφ(t) | of the Δθ(t) andδφ(t) are judged.

When the absolute values are changed greatly together, it is taken as avehicle lane change and it is taken off from an object to be corrected(step 704).

On the other hand when it is not judged so, it is taken as the object tobe corrected.

In a step 705, plus and minus of ΔωR(t) are judged. In case of ΔωR>0,the host vehicle is judged to be in the transition section 62, and the Ris corrected to be small as (R−ΔR) (step 706,).

In a case of ΔωR<0, the host vehicle is judged to be in the reversetransition section 64, and the R is corrected to be large as (R+ΔR)(step 707).

In a case of ΔωR=0, the host vehicle is judged to be in the circlecontour section 61, and the R is not corrected (step 708).

By the way, in a case that an warning and a ACC system are constitutedwith a millimeter wave radar as a key sensor, there are comparatively afew problems about a moving object such as the preceding vehiclesdriving.

However, in a case to perform the warning for forward stationary objector the ACC deceleration control, the millimeter wave radar can measurethe distance with a target, a relative velocity and angle in accurate,but it is difficult to recognize what it is.

For example, when there is a curve in a forward direction, even if it isassumed that a stationary object is caught on a forward drivingdirection, it is difficult to judge whether it is a stopping vehicle onan host vehicle lane or a road sign installed on the road side and overthe road.

In this way, the case that cannot be judged only with the millimeterwave radar exists sometimes.

So in FIG. 8, in order to judge the warning for the stationary objectprecisely, an embodiment is provided which has a CCD camera beinganother kind of a sensor in an embodiment of FIG. 1.

The same numerals are referred to the constitution to be same as theconstitution of an embodiment shown ahead in order not to repeat thesame description.

The figure shows a distance between the vehicles alarm system 70constituted by using signals from the millimeter wave radar, the gyrosensor, the steering sensor and the CCD camera.

In the figure, the CCD camera 71 is used for white line recognition 72usually by a photography pictorial image thereby, and has a zoom lensfunction.

On the other hand, the millimeter wave radar performs a stationaryobject sensing from a distance, a relative velocity and an angle.

When the millimeter wave detects the stationary object 23 forward now,the camera stops a white line recognition 72 temporarily and zoom up theforward stationary object which the millimeter wave caught.

The stationary object recognition 73 is performed, and whether it is anobstacle such as the stopping vehicle or not, and whether it isnon-obstacles such as a road sign outside of the road and an overheadbridge or not are judged.

Based on this stationary object recognition, the warning judgment 14 isperformed, an warning designation 15 for a stationary object isperformed and an alarm signal 16 is given to a driver display unit 17.

FIG. 9 shows an ACC System 75 similarly using signals from themillimeter wave radar, the gyro sensor, the steering sensor and the CCDcamera.

In the same way as the FIG. 8, a stationary object sensing—recognitionis performed, and an accelerating and decelerating judgment 25 of thevehicle is performed based on a signal from the stationary objectrecognition 73 (A reducing speed judgment for the stationary object).

FIG. 10 shows a case to distinguish the overhead bridge and the stoppingvehicle as one example of the stationary object.

The millimeter wave radar detects the overhead bridge in a considerablyforward position, 100-150 [m] ahead numerically.

In this period, it cannot be distinguished whether the forwardstationary object is the overhead bridge or the stopping vehicle.

When the detected stationary object is the stopping vehicle, it becomesnecessary to warn in this period because it takes much time for thedeceleration in a high-speed driving with more than 100 km per an hour.

Then, whether it is the overhead bridge or the road obstacle such as thestopping vehicle, is judged by performing the image processing using thecamera. The image processing means to distinguish the target by apattern matching and a sensing accuracy is not demanded so much.

As a result of discrimination, when it is taken as the overhead bridge,the alarm is not outputted.

In this way, it becomes possible to improve the accuracy of the warningby combining the target sensing by the millimeter wave with the targetdiscrimination by the camera image processing.

By the way, if it is assumed that the forward stationary object isdiscriminated and it is the obstacle such as the stopping vehicle on thevehicle lane, they are not complete as a judgment object for outputtingthe warning.

For example, in a cases that there is a branching road forward, andthere is a stopping vehicle on one side thereof, an accurate judgmentwhether the warning should be outputted is not performed if it is notunderstand which course the vehicle selects.

Then, in FIG. 11, a distance between the vehicles alarm system 76constituted by using a signal from a navigation system in addition tothe millimeter wave radar, the gyro sensor, the steering sensor, and theCCD camera. In the figure, a path judgment 78 is performed by using thenavigation system 77.

With the sensor except the navigation system, the stationary objectsensing and the stationary object recognition are performed, and it isassumed that the warning object such as the stopping vehicle is judged.

Then, according to a path judgment function 78 by the navigation system77, it is judged whether the warning object is on the driving vehiclelane in the future, and warning designation 15 is performed only when itis judged to be on the driving vehicle lane.

Accuracy of the warning designation 15 improves hereby.

In FIG. 12, an ACC system 75 constituted by using a signal from themillimeter wave radar, the gyro sensor, the steering sensor, the CCDcamera and the navigation system. In the figure, an accelerating anddecelerating judgment 25 is performed based on the signal by a pathjudgment 78.

Thereby the distance between the vehicles control is performed in highlyaccurate.

In the embodiment shown in FIG. 8 to FIG. 11 that mentioned the above,it was realized to alarm for a stationary object and to control it inhighly accurate by adding the camera and the navigation system inaddition to the millimeter wave radar.

In the following embodiment, the system which used only the gyro sensorand the steering sensor is provided as the millimeter wave radar and anauxiliary sensor shown in FIG. 1 and FIG. 2.

In this case, even if it is assumed that the circumstances is limited,it may be realized to alarm and control it in highly accurate by solvingthe following problems.

1. Cannot a curve to start with the forward host vehicle be estimated?

2. Cannot estimate where of center or side of the host vehicle lane thehost vehicle runs?

3. Cannot judge whether there is a stationary obstacle on the hostvehicle lane from a relationship of transfer objects?

They will be explained based on drawings as follows.

FIGS. 13(a), 13(b) shows two cases that a driving vehicle moves inforward of the host vehicle into lateral direction on the road havingplural driving vehicle lanes.

FIG. 13A shows a case that the host vehicle is before the curved roadand the forward preceding vehicle is on the curved road, and FIG. 13Bshows a case that the preceding vehicle changes the vehicle lane.

In FIG. 13A, the preceding vehicle is a object to be alarmed or befollowed continuously, and in FIG. 13B, the preceding vehicle becomesnot to be the following object.

When both is looked at from the host vehicle, the preceding vehiclelooks to move to the lateral direction, it can be distinguished from themovement of other vehicle.

In other words, forward vehicle 1 and forward vehicle 2, and thepreceding vehicle moved to the same lateral direction are detected, andit is judged to be the curved road when they moved to the same lateraldirection, and it is judged to be the vehicle lane change when theymoved to the different direction.

FIG. 14 is a flow chart showing steps to distinguish FIG. 13A and FIG.13B.

At first in step 1401, the velocity of the preceding vehicle (d1(t),θ1(t), Vf1(t)) is detected from a distance with the preceding vehicle 1at time t, the magnetic declination degree, and from the host vehiclevelocity and the relative velocity.

Similarly, relating to the forward vehicle 2, 3 except the host vehiclelane, (d2(t), θ2(t), Vf2(t)), (d3 (t), θ3(t), Vf3(t)) are detected. (Theforward vehicles to be detected is determined to be two here, howeverwhen it can be detected more, detected vehicle number may be increased).

In a step 1402 in the next, using data of past times t-1, t-2, . . . , adifferentiation filter process is performed, and the changes Δθ1(t),Δθ2(t), Δθ3(t) of θ1(t), θ2(t), θ3(t) are obtained.

In a step 1403, (Δθ1(t)/Vf1(t)), (Δθ2(t)/V f2(t)), (Δθ3(t)/Vf3(t)) areobtained.

These are equivalent to an angle which changes corresponding to thedriving distance of the vehicle, and it does not depend on the velocityof each vehicle. Using this in a step 1404, a transfer distance of thepreceding vehicle and forward vehicles 1, 2 is obtained so as to bejudged by obtaining ΔM12 and ΔM13 based on equations as follows.

ΔM12=|(Δθ1/Vf1)−(Δθ2/Vf2)|, and

ΔM13=|(Δθ1/Vf1)−(Δθ3/Vf3)|

The values of ΔM12 and ΔM13 are equal to or less than a predeterminedvalue, it is judged to be the transfer on a curve (step 1405).

On the other hand when it is bigger than the value, it is judged to bethe vehicle lane change (step 1406).

An example is shown here, in which, the host vehicle and the precedingvehicle runs at the center of a 3 vehicle lanes, and other onesrespectively run on right and left vehicle lanes.

If the forward vehicle except the preceding vehicle is caught on or morethan two vehicle lanes, a similar estimation may be performed.

However, estimation accuracy improves further when the more vehicles arecaptured.

Although the hypothesis is different from a cases that the forwardvehicle especially changes the vehicle lane, such a false estimation canbe avoid by increasing captured vehicle.

By the way in FIGS. 13(a) or (b) figure, in the host vehicle laneestimation, the vehicle lane position of the preceding vehicle is judgedby supposing that the host vehicle run the vehicle lane center.

For example, as shown it in FIG. 13A, the preceding vehicle and forwardvehicle run at the vehicle lane center, and the lateral position of eachvehicle is almost equal to the vehicle lane width Ly, there is not aproblem.

However, as in FIG. 13B, when the host vehicle, the preceding vehicle,and the forward vehicle deviate to one end of the vehicle lane, itbecomes difficult to understand which is the preceding vehicle.

Including this case, the driving position to the white line of the hostvehicle is estimated, and it is important to reflect it to the precedingvehicle judgment by offsetting the range of the host vehicle lane to theright or the left.

FIG. 15 shows a flow chart relating to a method to estimate the hostvehicle position and to offset the host vehicle lane position to theright or the left based on the estimated host vehicle position.

At first in a step 1601, the lateral position YL(t), YR(t) of the rightand the left forward vehicle, are obtained except one vehicle which isrecognized as the preceding vehicle. (When it cannot be judged as shownin the FIG. 13B, one in a side which the magnetic declination is small,is judged to be the preceding vehicle.)

In a step 1602, a moving average values <YL(t)>, <YR(t)> of YL(t), YR(t)which are sampled a predetermined times in the past.

In step 1603, corresponding to <YL(t)>, <YR(t)> obtained,Ly+ΔLy<{(<YL(t)>+<YR(t)>)/2>}<Ly−Δly is judged. (Here Ly: one vehiclelane width, ΔLy: value to be smaller than the one vehicle lane width).When the condition is not satisfied, it is assumed that reliability ofthe data is low, and it is not adopted.

When the condition is satisfied, the step 1604 is absorbed and is judgedaccording to the next equation.

When {<YL(t)>−Ly}>ΔLy and {<YR(t)>−Ly}<ΔLy it is judged as a right sidemoving.

When {<YL(t)>−Ly}<ΔLy and {<YR(t)>−Ly}>ΔLy it is judged as a left sidemoving.

When {<YL(t)>−Ly}<ΔLy and {<YR(t)>−Ly}<ΔLy it is judged as a center.

In a step 1605, the range of the host vehicle lane judgment is offset tothe right side or to the left side, or it is judged to be maintainedaccording to the result.

The above is a case in which the vehicles run at the center of the threevehicle lanes, and even if it is two vehicle lane or a forward road itis possible to be similar.

In this case, the forward vehicle in only one side or transversedirection distance with the forward vehicle are used for a reference,and reliability is improved by increasing number of the sample.

Further, in this method, because of a problem relating to aninstallation of the millimeter wave radar, even if when it must bemounted on the right or the left of the vehicle, it can be revised byestimating automatically.

A case that the preceding vehicle moves to the transverse direction andthe stationary object appeared over there, will be explained in thenext.

FIGS. 16A and 16B show a case that the preceding vehicle moves to thetransverse direction and the stationary object appeared over there.

Basically, an alarm is generated in FIG. 16A, and it is not generated inFIG. 16B.

However, because a course forward cannot be predicted, they can not bedistinguished.

Then, FIG. 17 shows a method to plan to distinct the both by payingattention to the transverse moving velocity of the preceding vehicle andthe pattern.

When, the transverse moving velocity of the preceding vehicle is shownwith a relationship with time as shown in the figure, the curved road isdetected showing a gentle change, however, in case of vehicle lanechange, the velocity is large at first because the steering angle islarge, and the lateral direction velocity disappears because thesteering is returned after the vehicle lane change, so that it isdetected as a variation of a convex shape.

The host vehicle closes to the stationary object while detecting themovement of the preceding vehicle, and a timing to alarm judgment attime T1, T2, and T3 according to the vehicle velocity of the hostvehicle and the distance between the cars, becomes different.

In cases of T2, T3, the judgment is easy, and the both can bedistinguished easily by detecting a changing pole point P of thepreceding vehicle driving speed.

On the other, in time T1, the both is needed to be distinguished on thebasis of one threshold value.

This threshold value is changed at any time according to the hostvehicle velocity, the preceding vehicle velocity, the preceding vehiclemagnetic declination degree, the host vehicle angular velocity and thedistance between the vehicles.

FIG. 18 shows a case that an oncoming vehicle goes across the stationaryobject which is more distant than the oncoming vehicle.

In such a case, it is not considered to be the stationary object whichis on the host vehicle lane and the alarm is not generated.

In such a method, the oncoming car is captured in a magnetic declinationdegree neighborhood of the stationary object caught at first, if thedistance between the vehicles is closer than the stationary object, thestationary object is considered to be outside of the vehicle lane and itis not an object to be generated the alarm.

In this case, this judgment is performed on the basis of a timedifference that caught the stationary object and the oncoming vehicleand by correcting the movement of the host vehicle.

As stated above, in the present invention,

A correct estimation equation of the preceding vehicle position isprovided, and a device which used it is proposed.

The correction amount is changed at an introduction part of the curve:angular velocity generation early stage (an increase direction), and ata rear part of the curve: angular velocity generate later stage (adecrease direction).

On the basis of the sensing positions of plurality of the precedingvehicles, white line position is estimated.

The curve forward and the branching are judged by detecting the movementamount in the lateral direction of the forward vehicle.

Judgment of the host vehicle lane and the position correction of thepreceding vehicle are performed by using both of the gyro sensor and thesteering sensor.

The lane position judgment of the preceding stationary object andpresence judgment of the stationary object warning are performed bymovement of the preceding vehicle.

The lane position of the preceding stationary object is judged by arelation with the oncoming vehicle.

The stationary object which is detected forward is recognized to be astationary target on the road and the warning is not generated when itis the stationary target.

When the stopping vehicle is captured on the driving lane, the drivinglane is judged whether it is a driving route of the host vehicle or not,and if it is judged to be the driving route of the host vehicle, awarning is generated.

A one body type millimeter wave radar system building in acommunications network facility and a judgment control function.

Effect of the Invention

As being constructed as above, the present invention has effects asfollows.

Distance of the host vehicle with the preceding vehicle is controlled tobecome a desired value, by detecting a preceding vehicle on a hostvehicle lane(including a stopping vehicle) using a millimeter waveradar, or when the host vehicle comes too much close with the precedingvehicle, a collision warning is generated.

In addition, a warning or the control (deceleration) can be performedonly the forward stopping vehicle of the host vehicle lane, bydistinguishing the stopping preceding vehicle from the road sign on theroad side and the stationary object such as the overhead bridge.

On the basis of movement of the preceding vehicle which the radar caughtand other sensor information, an accurate host vehicle lane estimationand a position correction of the vehicle can be performed in a curveroad.

The lane position estimation of the preceding vehicle is performed byreceiving various data from the vehicle side and by combining it withthe sensing information obtained by the millimeter wave radar, a warningand a control command information can be transmitted to the vehicleside.

What is claimed is:
 1. A vehicle control method comprising the steps of(a) detecting a velocity and angular velocity of a host vehicle, and adistance and a direction from said host vehicle to a preceding vehicleor a target, (b) calculating a next position of said preceding vehicleto said preceding vehicle or said target based on said velocity, angularvelocity and said direction detected in step (a), and (c) controllingsaid host vehicle so as to decelerate said host vehicle when said nextposition is in a predetermined range, wherein said predetermined rangeis set between a left position being apart to the left from a vehiclelane where said host vehicle runs as a half width Ly/2 of said vehiclelane and a right position being apart to the right from said vehiclelane as said half width Ly/2.
 2. A vehicle warning method comprising thesteps of (a) detecting a velocity and angular velocity of a hostvehicle, and a distance and a direction from said host vehicle to apreceding vehicle or a target, (b) calculating a next position of saidpreceding vehicle or said target based on said velocity, angularvelocity and said direction detected in step (a), and (c) generating awarning when said next position is in a predetermined range, whereinsaid predetermined range is set between a left position being apart tothe left from a vehicle lane where said host vehicle runs as a halfwidth Ly/2 of said vehicle lane and a right position being apart to theright from said vehicle lane as said half width Ly/2.
 3. A vehiclecontrol method comprising the steps of detecting a velocity and angularvelocity of a host vehicle, and a distance and a direction from saidhost vehicle to a preceding vehicle or a target, calculating a nextdistance from said host vehicle to said preceding vehicle or said targetbased on said velocity, angular velocity and said direction detected inthe former step, and controlling said host vehicle so as to deceleratesaid host vehicle when said next distance is smaller than apredetermined value, wherein said predetermined value is smaller than ahalf of a vehicle lane.
 4. A vehicle lane position estimation device forcapturing a preceding vehicle or a target by searching forward of anhost vehicle and estimating vehicle lane position thereof, said vehiclelane position estimation device, comprising means for measuring adistance TR between said host vehicle and said preceding vehicle or saidtarget, a direction angle α from said host vehicle, an angular velocityωs and a velocity Vs of said host vehicle, one vehicle lane sensingmeans for obtaining a lane Ly of a road, means for calculating a lateraldisplacement TC between said host vehicle and said preceding vehicle orsaid target, a longitudinal displacement TD therebetween and curvatureradius R of said host vehicle based on a following equation, T _(c) =T_(R) sin α,T _(D) −T _(R) cos α,R=Vs/ωs, means for calculating lateraldistance ΔR between said host vehicle and said preceding vehicle or saidtarget based on a following equation, ΔR={square root over((R−Tc)2+Tp2−R)} means for comparing Ly/2 with ΔR, and means for judgingsaid preceding vehicle or said target to be in a vehicle lane of saidhost vehicle when |ΔR|<Ly/2, and means for obtaining a judgment positionof a vehicle lane of said host vehicle by estimating a vehicle laneposition of plural said preceding vehicle and making a vehicle lanejudgment position of said preceding vehicle offset towards right or leftaccording to said vehicle lane position estimated.
 5. A vehicle laneposition estimation device for capturing a preceding vehicle or a targetby searching forward of an host vehicle and estimating vehicle laneposition thereof, said vehicle lane position estimation device,comprising means for measuring a distance TR between said host vehicleand said preceding vehicle or said target, a direction angle α from saidhost vehicle, an angular velocity ωs and a velocity Vs of said hostvehicle, one vehicle lane sensing means for obtaining a lane Ly of aroad, means for calculating a lateral displacement TC between said hostvehicle and said preceding vehicle or said target, a longitudinaldisplacement TD therebetween and a curvature radius R of said hostvehicle based on a following equation T _(c) =T _(R) sin α,T _(D) =T_(R) cos α,R=Vs/ωs, means for calculating lateral distance ΔR betweensaid host vehicle and said preceding vehicle or said target based on afollowing equation, ΔR={square root over ((R−Tc)2+Tp2−R)} means forcomparing Ly/2 with ΔR, and means for judging said preceding vehicle orsaid target to be in a vehicle lane of said host vehicle when |ΔR|<Ly/2,wherein a millimeter wave radar and a gyro sensor are used as said meansfor measuring.
 6. A vehicle lane position estimation device forcapturing a preceding vehicle or a target by searching forward of anhost vehicle and estimating vehicle lane position thereof, said vehiclelane position estimation device, comprising means for measuring adistance TR between said host vehicle and said preceding vehicle or saidtarget, a direction angle α from said host vehicle, an angular velocityωs and a velocity Vs of said host vehicle, one vehicle lane sensingmeans for obtaining a lane Ly of a road, means for calculating a lateraldisplacement TC between said host vehicle and said preceding vehicle orsaid target, a longitudinal displacement TD therebetween and a curvatureradius R of said host vehicle based on a following equation T _(c) =T_(R) sin α,T _(D) =T _(R) cos α,R=Vs/ωs, means for calculating lateraldistance ΔR between said host vehicle and said preceding vehicle or saidtarget based on a following equation, ΔR={square root over((R−Tc)2+Tp2−R)} means for comparing Ly/2 with ΔR, and means for judgingsaid preceding vehicle or said target to be in a vehicle lane of saidhost vehicle when |ΔR|<Ly/2, wherein a steering sensor and a gyro sensorare used as said means for measuring.
 7. A vehicle lane positionestimation device for estimating a position of a vehicle lane of astationary object (a forward stationary object) to be located before anhost vehicle, comprising a sensor configured and operative to measure adistance between said host vehicle and said preceding vehicle or anoncoming vehicle, a direction angle from said host vehicle, an angularvelocity and a velocity of said host vehicle, a vehicle lane sensorconfigured and operative to obtain a vehicle lane of a road, a deviceconfigured and operative to calculate a lateral displacement betweensaid host vehicle and said preceding vehicle or said oncoming vehicle, alongitudinal displacement therebetween and a curvature radius of saidhost vehicle, a device configured and operative to capture a forwardstationary object, a device configured and operative to obtain amovement of said preceding vehicle or a position of said oncomingvehicle, a device configured and operative to estimate a vehicle laneposition of said forward stationary object from a movement relationshipof said preceding vehicle obtained and said forward stationary objectcaptured or a position relationship with said oncoming vehicle, and adevice configured and operative to warn when said forward stationaryobject is in a vehicle lane of said host vehicle.
 8. A vehicle laneposition estimation device as defined in claim 7, further comprising adevice configured and operative to calculate a lateral distance ΔRbetween said host vehicle and said forward stationary object based onthe following equations T _(c) =T _(R) sin,T _(D) =T _(R) cos,R=Vs/Wsand ΔR={square root over ((R=Tc)2+Tp2−R)} wherein T is a distancebetween said host vehicle and said forward stationary object, angle fromsaid host vehicle, Ws velocity of said host vehicle, Vs velocity of saidhost vehicle, Tc lateral displacement, TD longitudinal displacement, andR curvature radius of said host vehicle.
 9. A vehicle lane positionestimation device as defined in claim 7, further comprising a deviceconfigured and operative to recognize whether said forward stationaryobject is an object on the road such as an overhead bridge.
 10. Avehicle lane position estimation device for capturing a precedingvehicle or a target by searching forward of an host vehicle andestimating vehicle lane position thereof, comprising apparatusconfigured and operable to measure a distance TR between said hostvehicle and said preceding vehicle or said target, a direction anglefrom said host vehicle, an angular velocity Ws and a velocity Vs of saidhost vehicle, a vehicle lane sensor configured and operative to obtain aroad lane Lly, a calculating apparatus configured and operable tocalculate a lateral displacement TC between said host vehicle and saidpreceding vehicle or said target, a longitudinal displacement TDtherebetween and curvature radius R of said host vehicle based on thefollowing equation, T _(c) =T _(R) sin,T _(D) =T _(R) cos,R=Vs/Ws acalculating apparatus configured and operable to calculate a lateraldistance R between said host vehicle and said preceding vehicle or saidtarget based on the following equation, ΔR={square root over((R−Tc)2+Tp2−R)} a comparator configured and operative to compare Ly/2with R, a judging apparatus configured and operable to judge saidpreceding vehicle or said target to be in a vehicle lane of said hostvehicle when 1R1<Ly/2, and an apparatus configured and operable toobtain a judgment position of a vehicle lane of said host vehicle byestimating a vehicle lane position of plural said preceding vehicle andmaking a vehicle lane judgment position of said preceding vehicle offsettowards right or left according to said vehicle lane position estimated.11. A vehicle lane position estimation device for capturing a precedingvehicle or a target by searching forward of an host vehicle andestimating vehicle lane position thereof, comprising a millimeter waveradar and gyro sensor configured and operative to measure a distance TRbetween said host vehicle and said preceding vehicle or said target, adirection angle from said host vehicle, an angular velocity Ws and avelocity Vs of said host vehicle, a vehicle lane sensor configured andoperative to obtain a road lane Ly, a calculator configured andoperative to calculate a lateral displacement TC between said hostvehicle and said preceding vehicle or said target, a longitudinaldisplacement TD therebetween and a curvature radius R of said hostvehicle based on the following equation T _(c) =T _(R) sin,T _(D) =T_(R) cos,R=Vs/Ws a calculator configured and operative to calculate alateral distance R between said host vehicle and said preceding vehicleor said target based on the following equation, ΔR={square root over((R−Tc)2+Tp2−R)} a comparator configured and operative to compare Ly/2with R, and an apparatus configured and operative to judge saidpreceding vehicle or said target to be in a vehicle lane of said hostvehicle when 1R1<Ly/2.
 12. A vehicle lane position estimation device forcapturing a preceding vehicle or a target by searching forward of anhost vehicle and estimating vehicle lane position thereof, comprising asteering sensor and a gyro sensor configured and operative to measure adistance TR between said host vehicle and said preceding vehicle or saidtarget, a direction angle from said host vehicle, an angular velocity Wsand a velocity Vs of said host vehicle, a vehicle lane sensor configuredand operative to obtain a road lane Ly, a calculator configured andoperative to calculate a lateral displacement TC between said hostvehicle and said preceding vehicle or said target, a longitudinaldisplacement TD therebetween and a curvature radius R of said hostvehicle based on the following equation T _(c) =T _(R) sin,T _(D) T _(R)cos,R=Vs/Ws a calculator configured and operative to calculate a lateraldistance R between said host vehicle and said preceding vehicle or saidtarget based on the following equation, ΔR={square root over((R−Tc)2+Tp2−R)} a comparator configured and operative to compare Ly/2with R, and an apparatus configured and operative to judge saidpreceding vehicle or said target to be in a vehicle lane of said hostvehicle when 1R1<Ly2.